Belt retractor having a force limiter

ABSTRACT

The invention relates to a belt retractor comprising a frame ( 10 ), a belt reel ( 12 ) rotatably arranged within the frame ( 10 ), a blocking mechanism ( 18 ) by which the belt reel ( 12 ) can be blocked within the frame ( 10 ), and a load limiter which comprises a corrugated disk ( 36 ), characterized in that the corrugated disk ( 36 ) is disposed between the belt reel ( 12 ) and a cover ( 38 ) which is laterally attached to the belt reel ( 12 ).

RELATED APPLICATIONS

This application corresponds to PCT/EP2017/058075, filed Apr. 5, 2017,which claims the benefit of German Application No. 10 2016 106 303.7,filed Apr. 6, 2016, the subject matter of which are incorporated hereinby reference in their entirety.

BACKGROUND OF THE INVENTION

The invention relates to a belt retractor comprising a frame, a beltreel rotatably disposed in the frame, a blocking mechanism by which thebelt reel can be blocked within the frame, and a load limiter includinga corrugated disk.

Said belt retractor is known from DE 10 2008 063 639 A1. It serves forproviding a seat belt for a vehicle occupant of an automotive vehicle.During normal operation the vehicle occupant can freely unwind the seatbelt from the belt reel against the action of a wind-up spring, and thebelt reel winds up the seat belt again when the vehicle occupantunfastens the seat belt, for example. In response to externalparameters, such as, for example, the deceleration of the vehicle or therotational acceleration of the belt reel during webbing extension, theblocking mechanism by which the belt reel can be blocked within theframe is activated.

When the belt reel is blocked within the frame, until a predefined loadlevel is reached within the seat belt no more seat belt can be unwoundfrom the belt reel; the belt reel does not rotate relative to the frameof the belt retractor, apart from minimum yielding which is due to theinherent elasticity of all components present in the flux of force.

When the predetermined load level is reached, the load limiter willbecome active. It enables the belt reel to rotate relative to the frameunder the effect of the tensile load of the seat belt. In this way, aparticular amount of seat belt is released which is available as anadditional path for the deceleration of the vehicle occupant.

The load limiter employed here usually is a torsion rod which at one endis fixedly coupled to the belt reel and at the other end is fixedlycoupled to the frame.

Up-to-date belt retractors usually comprise a second load limiter to theload level of which it will be changed when the afore-describedload-limiting phase has been completed. In the second phase of loadlimitation, too, a particular amount of seat belt can be unwound fromthe belt reel. The load required to this end within the seat belt isbelow the load during the first load-limiting phase, however, in whichthe two load limiters usually are active in parallel so that the loadlevel thereof is added up.

The two load-limiting phases usually are adapted to each other so thatthe first load-limiting phase enables the thorax of the vehicle occupantto move forward until it contacts an airbag, and the secondload-limiting phase enables the thorax of the vehicle occupant toimmerse into the airbag.

In the belt retractor known from the afore-mentioned document DE 10 2008063 639 A1 the second load limiter is formed by the corrugated diskwhich can be clamped between two corrugated surfaces and can be rotatedrelative to the latter so that it has to meander between the twocorrugated surfaces.

SUMMARY OF THE INVENTION

It is the object of the invention to impart a compacter design to thebelt retractor.

For achieving this object in a belt retractor of the type mentioned inthe beginning the corrugated disk is provided to be arranged between thebelt reel and a cover which is attached laterally to the belt reel. Inthis way, a design which is especially compact in the axial directioncan be obtained. In accordance with one embodiment of the invention, thecorrugated disk is provided to be flat in the initial condition. Thisresults in the fact that the corrugated disk is retained, in the mountedstate, between the cover and the belt reel in a corrugated condition sothat, due to its inherent elasticity, it is adjacent with a bias to thededicated surfaces.

One of said surfaces is a first corrugated surface dedicated to the beltreel. Said corrugated surface rotates along with the belt reel.

Basically, it is possible that the first corrugated surface is providedon a separate component which is mounted to the belt reel. Preferably,the first corrugated surface is directly formed by an end face of thebelt reel, however. In this way, the axial construction length isminimized as no separate component is required for the second corrugatedsurface.

Another one of the surfaces with which the corrugated disk interacts isa second corrugated surface dedicated to the cover. The secondcorrugated surface, too, is coupled to the belt reel in a rotationallyfixed manner so that it co-rotates with the latter.

The second corrugated surface may basically be arranged on a componentseparate from the cover. Of preference, the second corrugated surface isformed by the inner surface of the cover, however. In this manner, theaxial construction space is further reduced.

Preferably, the corrugated surface has a sinusoidal contour. Thesinusoidal contour excels by a smooth transition between raised andrecessed portions so that the corrugated disk is gently deformed when itis rotated between the corrugated surfaces.

The cover is preferably connected to the belt reel in a rotationallyfixed manner. Accordingly, the second corrugated surface dedicated tothe cover is ensured to co-rotate with the belt reel.

Preferably, the cover is provided with plural lands engaging in recessesin the belt reel. In this way, a very simple rotational drive can beachieved.

Preferably, the belt reel and the cover are fastened to each other inthe axial direction by means of a crimping ring. The latter is attachedto the cover from outside and is flanged or crimped on its side facingthe belt reel so that it encompasses a flange of the belt reel. Thus,the cover is reliably fastened to the belt reel in the axial direction.

According to one configuration of the invention the corrugated disk isprovided to have a driving design at its inner circumference. Thedriving design at the inner circumference enables a torque to be exertedon the corrugated disk while at the same time a compact design ismaintained.

The driving design may be a collar which is formed integrally with thedisk-shaped portion of the corrugated disk and has a toothed profile.This type of driving design may be produced at low cost by plasticallyreshaping a disk-shaped blank.

Preferably, the driving design is connected in a rotationally fixedmanner to a torsion rod which constitutes a second load limiter. Due toits arrangement along the axis of rotation of the belt reel, the torsionrod is especially suited for introducing a torque into the corrugateddisk.

Preferably, the corrugated disk is provided to be connected to the beltreel at one end of the belt reel and the torsion rod is provided to beconnected to the belt reel at the other end. In this design, the loadlimiter formed by the corrugated disk is automatically connected inparallel to the load limiter formed by the torsion rod.

BRIEF DESCRIPTION OF THE DRAWINGS

Hereinafter the invention shall be described by way of an embodiment asillustrated in the attached drawings, wherein:

FIG. 1 shows an exploded view of the belt retractor according to theinvention;

FIG. 2 shows a section across the belt retractor of FIG. 1;

FIG. 3 shows a diagram of the acting webbing load over the length ofextended webbing;

FIGS. 4a to 4c show a perspective view of different steps of mountingthe corrugated disk to the belt reel;

FIGS. 5a and 5b show a schematic sectional view of two steps whenmounting the corrugated disk to the belt reel;

FIGS. 6a and 6b show a schematic section of the corrugated disk betweenthe corrugated surfaces associated therewith during the mounting stepsof FIGS. 5a and 5 b;

FIG. 7 shows a perspective partially cut view of the corrugated disk inthe completely mounted state;

FIG. 8 shows a detail of the corrugated disk disposed between thecorrugated surfaces in a schematic sectional view;

FIG. 9 shows a perspective view of the completely mounted belt reel;

FIG. 10 shows a section across the belt reel of FIG. 9;

FIG. 11 shows a section along the plane XI-XI of FIG. 10;

FIG. 12 shows an exploded view of an actuator employed in the beltretractor of FIG. 1;

FIG. 13 shows a perspective partially cut view of the actuator of FIG.12 mounted on the belt retractor, with the actuator being provided inthe initial position;

FIG. 14 schematically shows a broken-away sectional view across the beltretractor of FIG. 13 on the side of the belt reel provided with theactuator;

FIG. 15 shows a view corresponding to that of FIG. 13, with the actuatorbeing provided in the released state; and

FIG. 16 shows a view corresponding to that of FIG. 14, with the actuatorbeing provided in the released state.

DESCRIPTION

By way of FIGS. 1 and 2, initially the general structure of the beltretractor is explained.

The belt retractor as a self-supporting component includes a frame 10 inwhich a belt reel 12 is arranged.

A torsion rod 14 which is the core part of a load limiter extendsthrough the belt retractor. The torsion rod 14 is dedicated at one end(the left end in the Figures) to the belt reel 12 and at the other end(the right end in the Figures) is accommodated in a hub 16 in arotationally fixed manner. At the hub a blocking mechanism 18 notexplained in more detail here is disposed which serves for blocking thehub 16 fixedly relative to the frame 10, where necessary.

Also, a drive wheel 20 is connected to the hub 16 in a rotationallyfixed manner, with a so-called pre-tensioner, for example an electricmotor, or a main tensioner, for example a load transmission element 24adjustable in a piston 22 visible in FIG. 13 by a pyrotechnical charge,being capable of acting upon said drive wheel.

The effects of the pre-tensioner and of the main tensioner are generallyknown and therefore shall be explained only roughly here. Thepre-tensioner serves for rotating the belt reel in the windingdirection, where necessary, so that the webbing is tensioned up to aparticular pre-tensioning load. This operation is reversible. The maintensioner serves for driving the belt reel in the winding direction,where necessary, so that a definitely higher tensioning load is obtainedwithin the webbing. The main tensioner can be activated merely once.

At its end associated with the belt reel 12 the torsion rod 14 isprovided with a driving toothing 26 in which the points of plural bars28 engage, the bars being arranged in corresponding recesses 30 of thebelt reel. There the bars 28 are retained by a support ring 32 which isfixed on the belt reel 12 by means of a holder 34.

When a torque is exerted on the belt reel 12, for example by tensionacting on the seat belt, said torque is transmitted via the edges of therecesses 30 and the bars 28 to the torsion rod 14 and from there intothe hub 16. Assuming that the hub 16 is blocked fixedly relative to theframe, also the belt reel 12 is prevented from rotating relative to theframe, in any case as long as the acting torque is below the torque atwhich the torsion rod 14 is plastically twisted. The load transmissionpath mentioned here is indicated by broken lines in FIG. 2 withreference numeral I.

On the side of the belt reel 12 opposed to the bars 28, a corrugateddisk 36 which is a central component of a further load limiter isarranged. The corrugated disk 36 is connected to the torsion rod 14 in arotationally fixed manner at the end thereof associated with the hub 16and is elastically clamped in the axial direction between an end face ofthe belt reel 12 and a cover 38.

The corrugated disk 36 may be rotated between the belt reel 12 and thecover 38, when the acting torque is higher than a holding torque of thecorrugated disk 36 which is composed of a friction component and aresistance of the corrugated disk against deformation.

With respect to the second load limiter, a second load path inserted inFIG. 2 by broken lines with reference numeral II extends from the beltreel to the corrugated disk, from the corrugated disk into the torsionrod and from the latter ultimately into the hub 16.

By way of FIG. 3, the load limitation shall be explained as follows.

In the initial condition, both the load limiter utilizing the torsionrod 14 and the load limiter utilizing the corrugated disk 36 are active.In the diagram of FIG. 3, this corresponds to a webbing extension froms₁ to s₂. In this phase, the two load limiters act in parallel so thatin the seat belt a total load F_(G) is resulting herefrom which iscomposed of a load F_(I) defined by the torsion rod 14 and a load F_(II)defined by the corrugated disk 36.

At the point s₂ the load limiter utilizing the torsion rod 14 isswitched off so that only the load limiter utilizing the corrugated disk36 continues to be active. Accordingly, the load within the webbingdecreases to the load F_(II).

Hereinafter, the structure of the load limiter comprising the corrugateddisk 36 shall be explained in detail by way of FIGS. 4 to 8.

The corrugated disk 36 has a flat disk-shaped portion 40 in the initialcondition.

At its inner circumferential edge, the corrugated disk 36 includes acollar 42 extending in the axial direction. The collar 42 is formedintegrally with the disk-shaped portion 40 and shows a driver design,here in the form of a toothed profile.

The toothed profile of the driver design 42 of the corrugated disk 36 isfixedly attached to an external toothing 44 by which the torsion rod 14is also fixedly accommodated within the hub 16. Thus, the corrugateddisk 36 is coupled in a rotationally fixed manner both to the right endof the torsion rod 14 in the Figures and to the hub 16.

The corrugated disk 36, more exactly speaking the disk-shaped portion 40thereof, is arranged between a first corrugated surface 46 and a secondcorrugated surface 48.

The first corrugated surface 48 is one of the end faces of the belt reel12. As is evident especially from FIG. 4a and from FIG. 7, the firstcorrugated surface 48 is provided with a sinusoidal profile at its edgelocated outside in the radial direction (cf. also FIG. 8). As is evidentfrom the projection P of the profile of the first corrugated disk 48related to FIG. 7, the outer circumference A extends in sinusoidalshape, while the inner circumference I forms a flat circle. For theconcrete contour at the outer circumference, the following formula hasturned out to be useful (cf. also the coordinate system inserted in FIG.8): y=0.8·sin x.

The second corrugated surface 48 is configured as the inner surface ofthe cover 38. The contour of the second corrugated surface 48corresponds to the contour of the first corrugated surface 46: At theinner circumference of the cover 38 the second corrugated surface 48extends along a flat circle, while the second corrugated surface shows asinusoidal curve at its outer circumference (cf. especially FIG. 4a ).

When the corrugated disk 36 is mounted, it is pushed onto the torsionrod 14 disposed within the belt reel 12, and more exactly speaking, tothe outer toothing 44 thereof (cf. FIGS. 4a and 4b ). Subsequently, thecover 38 is pushed on in the axial direction, wherein said cover isprovided with plural lands 50 which engage in corresponding recesses 52being provided outside the first corrugated surface 46 at the outercircumference of the belt reel 12. In this way, the cover 38 is fixed tothe belt reel 12 in a rotationally fixed manner (cf. FIG. 4c ), but inthe pre-assembled state it is axially movable.

In said pre-assembled state, the disk-shaped portion 40 of thecorrugated disk 36 defines the distance between the first and secondcorrugated surfaces 46, 48 (cf. FIGS. 5a and 6a ).

In order to completely mount the corrugated disk 36 with respect to itsfunction as a load limiter, a crimping ring 54 having a C-shapedcross-section in the initial condition is pushed onto the cover 38. Thecover 38 together with the crimping ring 54 then is pressed against thebelt reel 12 in the axial direction until the disk-shaped portion 40 ofthe corrugated disk is deformed between the two corrugated surfaces 46,48 (cf. especially FIG. 6b ), and the portion of the crimping ring 54dedicated to the belt reel 12 is flanged or crimped in the direction ofthe arrow P of FIG. 5b so that the cover 38 is tightly attached to thebelt reel 12 in the axial direction. Inside the end face of the beltreel 12 forming the first corrugated surface 46, the torsion rod 14 issupported in a bearing ring 39 in the area of the outlet from the beltreel 12. In this way, also the corrugated disk is centered between thebelt reel 12 and the cover 38.

When considering, for example, FIGS. 5b and 6b , it is evident that,when the belt reel 12 is rotated relative to end of the torsion rod 14provided with the external toothing 44, the corrugated disk 36 rotatesrelative to and between the corrugated surfaces 46, 48. The corrugateddisk 36 counters said rotation by a resistance moment that is composedof a friction component and a deformation force component.

The friction component is defined by the surface nature and the contactforce between the corrugated disk 36, on the one hand, and the twocorrugated surfaces 46, 48, on the other hand. The deformation forcecomponent is defined by the resistance of the disk-shaped portion 48which the latter sets against continuous deformation along thesinusoidal contour of the two corrugated surfaces 46, 48. In otherwords: By rotation of the corrugated disk 36 relative to the corrugatedsurfaces 46, 48 the corrugated disk 36 will be continuously bent inopposite directions especially along its outer circumference.

By way of the FIGS. 9 to 14, the structure of the load limiter utilizingthe torsion rod 14 shall hereinafter be described.

It is the substantial characteristic of the load limiter utilizing thetorsion rod 14 that the belt reel 12 can be uncoupled from the torsionrod 14. In this state, solely the load limiter utilizing the corrugateddisk 36 is active.

In the initial condition of the belt retractor, viz. during “normaloperation”, the belt reel 12 is tightly coupled to the torsion rod 14,however. For this purpose, the bars 28 already mentioned before are usedwhich are arranged in recesses 30 of the belt reel 12.

The bars 28 are illustrated more clearly in the FIGS. 10 and 11. Attheir radially inner end, they include two teeth 60 which engage in thedriving toothing 26 of the torsion rod 14.

In the position shown in FIG. 11 in which the bars 28 are located insidethe recesses 30 and the teeth 60 engage in the driving toothing 26, atorque can be transmitted from the belt reel 12 to the torsion rod 14.This is accomplished by the fact that the edge of the correspondingrecess 30 located at the rear in the direction of rotation drives thebar 28 and the latter in turn rotates the driving toothing 26 of thetorsion rod 14 via the flanks of the teeth 60 located at the front inthe circumferential direction.

The support ring 32 is in charge of the fact that during torquetransmission the bars 28 are not outwardly pressed out of the recesses30. More exactly speaking, each of the bars 28 abuts, with a shoulder62, on the inner circumference of the support ring 32.

The support ring 32 in this case is provided with a support collar 64bent in the axial direction.

In the position shown in the FIGS. 9 to 14, the support ring 32 is fixedby the holder 34 briefly mentioned in the foregoing.

The holder 34 is a plastic injection-molded part which is cage-shaped.In the broadest sense, the holder 34 is ring-shaped so that it is pushedonto an extension 13 of the belt reel 12.

The holder 34 includes plural radially inwardly effective detent arms 66by which it is fixed on the belt reel 12 in the axial direction.

Moreover, the holder 34 includes plural radially outwardly actingretaining arms 68 to which the support collar 64 of the support ring 32is adjacent. In this way, the support ring 32 is fixed on the belt reel12 in the axial direction so that it supports the bars 28 in the radialdirection in order to prevent the latter from leaving the recesses 30when a torque is transmitted from the belt reel to the torsion rod.

In order to release the coupling between the belt reel 12 and thetorsion rod 14, the support ring 32 may be displaced in the axialdirection until it stops supporting the bars 28 in the axial direction.For this purpose, an actor 70 is provided, as especially shown in FIG.12.

The actor 70 comprises a case 72 in which a lifting ring 74 is rotatablyaccommodated. The lifting ring includes, along its outer circumference,plural radially orientated abutting edges 76 which are provided forinteracting with lifting ramps 78 being disposed in the case.

When the lifting ring 74 is in its initial position, the abutting edges76 abut on the “lower” end of each lifting ramp 78, viz. relating toFIG. 13 in the area of each lifting ramp respectively provided furtherclockwise. When the lifting ring is rotated relative to the liftingramps 78 (anti-clockwise relating to FIG. 13), the abutting edges 76slide along the lifting ramps 78 so that the lifting ring 74 is shiftedin the axial direction.

For shifting the lifting ring 74 a so-called micro-gas generator 80 isprovided which may be, for example, an igniter for a “large” gasgenerator as it is used to deploy a driver or passenger airbag.Basically, however, also any gas generator may be used which generatesthe desired amount of compressed gas within the desired period of time.

The micro-gas generator 80 is accommodated in a seat 82 within the case72 which hereinafter shall be referred to as lifting case due to thelifting movement of the lifting ring 74 produced.

In the case 72 also a piston 84 which is in fluid communication with themicro-gas generator 80 is accommodated. The piston 84 abuts on anactuating tab 86 projecting from the lifting ring 74 in the radialdirection. The actuating tab 86 in this case is formed integrally withthe lifting ring.

The lifting case 72 is attached to the frame 10 in the completelymounted state of the belt retractor (cf. FIGS. 13 and 14). The liftingring 74 is provided in an initial position in which it is approximatedto the leg of the frame 10 at which the lifting case 72 is disposed. Thelifting ring 74 is located inside the support ring 32, i.e. between thesupport ring 32 and the area of the belt reel onto which the seat beltis wound.

The lifting ring is retained in its initial position by fixing tabs 73so that there will be no friction with the support ring 32 co-rotatingwith the belt reel 12.

The micro-gas generator 80 is locked in the seat 82 associated therewithwithin the lifting case 72 by means of a retaining clip 90 (cf.especially FIG. 12).

The retaining clip 90 is a bent sheet metal part including a bracket 92,a retaining portion 94 closed in the circumferential direction and twodetent arms 96.

The bracket 92 is hooked in a counter bearing 98 provided at the liftingcase 72 laterally from the seat 82 for the micro-gas generator 80.

The retaining portion 94 abuts on a shoulder 81 provided at themicro-gas generator 80 on the side facing away from the piston 84. Sincethe retaining portion 94 is closed in the circumferential direction,i.e. is ring-shaped, it is prevented from slipping off the micro-gasgenerator 80.

The detent arms 96 engage in appropriate recesses on the side of thelifting case 72 facing away from the counter bearing 98 laterally fromthe seat 82. As is evident especially from FIG. 14, the detent arms 96,which are located behind the sectional plane in this sectional view andtherefore are not visible in FIG. 14, abut on the leg of the frame 10 onwhich the lifting case 72 is arranged. Therefore, they are pressedtightly against the lifting case 72 by the respective housing leg sothat there they are prevented from leaving the detent recessesassociated with them.

In this way, the micro-gas generator 80 is positioned with littleeffort, though very reliably, in the dedicated seat 82 within thelifting case 72.

When, starting from the state as shown in FIGS. 13 and 14, the micro-gasgenerator 80 is ignited, the piston 84 in the lifting case 72 is shiftedso that the lifting ring (relating to FIGS. 13 and 15) is rotatedanti-clockwise. The lifting ring 74 then performs, due to the liftingramps 78, an axial stroke, namely away from the leg of the frame 10 onwhich the lifting case 72 is arranged outwardly in the axial direction(cf. FIGS. 14 and 16).

During said stroke the support ring 32 is shifted relative to the holder34 in the axial direction so far that the action of the retaining arms68 is overcome and the support ring 32, when viewed in the axialdirection, is located outside the bars 28 (cf. especially FIG. 16).

In this condition of the support ring 32, the bars 28 may yieldoutwardly in the radial direction, when a torque is transmitted betweenthe belt reel 12 and the torsion rod 14. Said radial movement of thebars 28 is assisted by the flanks of the teeth 60 and of the drivingtoothing 26 being inclined so that a force acting radially outwardly onthe bars 28 is generated.

The invention claimed is:
 1. A belt retractor, comprising a frame (10), a belt reel (12) rotatably arranged within the frame (10), a blocking mechanism (18) by which the belt reel (12) can be blocked within the frame (10), a cover (38) laterally attached to the belt reel (12) in a rotationally fixed manner, and a load limiter which comprises a corrugated disk (36) disposed between the belt reel (12) and the cover (38).
 2. The belt retractor according to claim 1, wherein the corrugated disk (36) is flat in the initial condition.
 3. The belt retractor according to claim 1, wherein the corrugated disk (36) abuts on a first corrugated surface (46) dedicated to the belt reel (12).
 4. The belt retractor according to claim 3, wherein the first corrugated surface (46) is formed by an end face of the belt reel (12).
 5. The belt retractor according to claim 3, wherein the corrugated surface has a sinusoidal contour.
 6. The belt retractor according to claim 3, wherein the corrugated disk (36) abuts on a second corrugated surface (48) dedicated to the cover (38).
 7. The belt retractor according to claim 6, wherein at least one of the corrugated surfaces (46, 48) has a sinusoidal contour.
 8. The belt retractor according to claim 1, wherein the corrugated disk (36) abuts on a second corrugated surface (48) dedicated to the cover (38).
 9. The belt retractor according to claim 8, wherein the second corrugated surface (48) is formed by an inner surface of the cover (38).
 10. The belt retractor according to claim 1, wherein the cover (38) is provided with plural lands (50) which engage in recesses (52) in the belt reel (12).
 11. The belt retractor according to claim 1, wherein the belt reel (12) and the cover (38) are fastened to each other in the axial direction by means of a crimping ring (54).
 12. The belt retractor according to claim 1, wherein on its inner circumference the corrugated disk (36) is provided with a driving design (42).
 13. The belt retractor according to claim 12, wherein the driving design is a collar (42) which is formed integrally with the disk-shaped portion (40) of the corrugated disk (36) and has a toothed profile.
 14. The belt retractor according to claim 12, wherein the driving design (42) is connected to a torsion rod (14) constituting a second load limiter in a rotationally fixed manner.
 15. The belt retractor according to claim 14, wherein the corrugated disk (36) is connected to the belt reel (12) at one end of the belt reel (12) and the torsion rod (14) is connected to the belt reel (12) at the other end thereof.
 16. A belt retractor, comprising: a frame (10); a belt reel (12) rotatably arranged within the frame (10); a blocking mechanism (18) by which the belt reel (12) can be blocked within the frame (10); a cover (38) laterally attached to the belt reel (12); a first load limiter including a torsion rod (14) extending through the belt reel (12); and a second load limiter including a corrugated disk (36) disposed between the belt reel (12) and the cover (38), an inner circumference of the corrugated disk (36) being connected to the torsion rod (14) in a rotationally fixed manner.
 17. The belt retractor according to claim 16, wherein the inner circumference the corrugated disk (36) includes a driving design (42), the driving design (32) being connected to the torsion rod (14) in a rotationally fixed manner.
 18. The belt retractor according to claim 17, wherein the driving design is a collar (42) which is formed integrally with the disk-shaped portion (40) of the corrugated disk (36) and has a toothed profile.
 19. The belt retractor according to claim 16, wherein the corrugated disk (36) is connected to the belt reel (12) at one end of the belt reel and the torsion rod (14) is connected to the belt reel at the other end of the belt reel.
 20. The belt retractor according to claim 16, wherein the cover (38) is connected to the belt reel (12) in a rotationally fixed manner. 